The knee to the groin defense is not all it's cracked up to be because most men will protect that area. Learn to hit the eyes with your fingertips, the neck with the inside of your hand--thumb tucked under the fingers--, learn to use the heel of your hand as the striker (because most people make really bad fists which are more likely to hurt you by breaking your fingers or wrists than hurt the attacker when you strike) and learn to use the elbows. Kicks are foolish for most people to use because they are seldom fast enough to hit the target, and if your feet are not held purposely in a given way, you will break the mechanism that provides your best defense: running away.

Most people are not mentally prepared to gouge an eye out or rip off an ear. Unless you are, you will likely lose unless your training has been purposeful and lengthy. Lengthy means that you'd require at least two years at a few hours every day with a good instructor, and then you'd require to continue that training for the rest of your life. Also, it's best to take a training wherein you get struck by the people with whom you spar, because if you can't handle the first few hits to your body, all the martial arts in the world ain't gonna help you.

Learn the strike areas and be prepared to hit the attacker in those areas. These areas will be easy to find once you learn some basic anatomy. You can interrupt the heart rhythm with a palm strike. You can rupture a spleen or severely damage a liver with a finger strike. You can blind someone with your fingers, break an eardrum with your palm. You can crack ribs with the heels of your palms. If you are fortunate enough to knock your opponent off balance, please be prepared to crush his larynx with the heel or side of your foot. If he's face down, drop your body weight and use your knees to rupture one or both kidneys. If you are not prepared to do that, then you were in the wrong place to begin with, and you fooled yourself into thinking that you were prepared for self defense. Few people are trined well enough for self defense that does not involve causing serious injury to an attacker.

All the 'what if he does this' fighting bologna means little on the streets. Chances are he's had some training also, and he ain't gonna DO that.

Be aware--or as the aviators say, "Check your six!" Always. Be aware of what's going on around you at all times, and when situations seem to be getting tense, it's time to leave. Do so. There are no good or bad guys in fights on the street. There are those who leave and those who don't. The best weapon you have is your brain. Use it to stay away from bad situations. Walk wide at corners; stay near the curb when you pass buildings; walk two blocks out of your way if six or seven people are 'hanging around' on a street at night; walk in the park with some friends--and night is a really stupid time to do that. If you work a late shift and you don't feel safe going to your vehicle, ask your company to have someone escort you or ask a friend to come meet you. Rule #1: Do NOT be where the shit hits. Rule #2: See Rule #1.